Unsupported - Cython Wiki

See also the relevant section of enhancements.

Unsupported Python Features

One of our goals is to make Cython as compatible as possible with standard Python. This page lists the things that work in Python but not in Cython.

def make_func():
    def f(x):
        return x*x
    return f

(work in progress) This relies on functional closures

Using the yield keywords. (work in progress) This relies on functional closures

a = b%c

where b and c are floats will raise the error "Invalid operand types for '%' (float; float)"

This can currently be worked around by putting

cdef extern from "math.h":
    double fmod(double x, double y)

somewhere is the source file and then using

a = fmod(b,c)

Class and function definitions cannot be placed inside control structures.